366 BULLETIN OF THE 



between the first antennae, and on each side in front of the eyes. Eyes 

 round. Epimera of the first four thoracic segments produced into prominent 

 spines. The spines of the first and second pair are of about the same length ; 

 the third somewhat longer ; the fourth longest, being about twice as long as 

 the third, and exceeding the breadth of the broadest segment of the body. 

 The first three pairs are directed downward and forward, while the fourth 

 project at nearly right angles to both the longitudinal and vertical axes of 

 the body. Telson broad, entire. 



Peduncle of first antenna reaching the middle of the last segment of the 

 peduncle of second antenna? ; flagellum composed of twelve segments. Sec- 

 ond antenna much longer than first antenna ; basal segment clearly separated 

 from the head ; olfactory denticle prominent ; flagellum composed of thirteen 

 segments. Carpopodite of first pair of legs triangular, as broad as the pro- 

 podite, furnished with seta? on its distal margin ; palm of propodite slightly 

 concave, transverse ; dactylopodite curved. Second pair of legs in the male 

 very large; meropodite armed with prominent setae at the antero-inferior 

 an^le; carpopodite with a long process, setiferous at its extremity, projecting 

 downward and forward between the propodite and the meropodite ; propodite 

 lar^e, convex above and below, palm oblique, straight, with small setae ; dac- 

 tylopodite slender, curved. In the female, the second pair of legs are 

 smaller, the propodite similar to the corresponding segment of the first pair, 

 and not broader than the meropodite ; the palm nearly perpendicular to the 

 straight lower margin ; lower angle of the meropodite projecting under the 

 propodite as a blunt process, much shorter than the same process in the 

 male. Fifth pair of legs about as long as the fourth. Sixth and seventh of 

 about equal length, much longer than the fifth ; when extended backward 

 reaching considerably beyond the end of the longest caudal stylets. Hind 

 margin of the basipodites of the fifth, sixth, and seventh pair of legs slightly 

 serrate. Third pair of caudal stylets very small, curved upward, so as to 

 project but little beyond the telson. 



The shell viewed under the microscope is furnished with rows of very 

 minute hairs, arranged as in Fig. 18. 



Length from front of head to end of telson, 8 mm - to 10 rai »- Breadth from 

 tip to tip of fourth pair of epimeral spines, C mm - to 10 mm - 



Collected at the following places in the lake: — 



i^'Achacache, 11 fathoms, countless specimens. 



llulfofPuno, 88 specimens. 



Gulf of Desaguadero, 1 specimen. 



i Chuquito, 40 fathoms, 4 specimens. 



i-^uli, 60 fathoms, 25 specimens. 



Between Taquili and Amantane, 66 fathoms, 2 specimens. 



This seems to be the commonest crustacean of Lake Titicaca. The length 



